On a quest for the mead of wisdom

Historical Brewing 201: OK, Sometimes, It’s as Hard as You Think

I’ve talked at you all before about how easy it can be to do historical brewing research and recreation. We often attempt to take the principles of period processing methods and attempt to translate them into modern methodology, to give a sense of historical practice by varying the familiar.

We can also alter ingredient bills, to attempt to emulate the flavor profiles that may have existed at the time. This is all well and good, and it’s an important part of the process of experimental recreation.

Sometimes, though, the task is not so clear-cut, and attempting accurate recreation becomes a real challenge. How were the ingredients grown? What units of measurement were at play? Water quality? We can’t always answer all of these questions, but the attempt to do so can yield valuable information, and the process of extrapolating will teach us things whether or not we get a useful end-product.

So let’s talk about wood.

SEE WHAT I DID THERE?(Archaeological Museum of Baden-Württemberg. Photo: Manuela carpenter – click for a link to the gallery page)

This bottle is part of an excavation of Trossingen grave 58, a find in Germany that dates to the 6th century CE. The picture above links to a gallery of the find.

This bottle is identified as a vessel with the remains of a hopped barley beer. This is sort of A Big Deal in the historic brewing world, because this would constitute the oldest existing physical evidence of the use of hops in a fermented beverage ever found. Not only that, but this is solid physical evidence of the use of hops a good 500 years before we had thought hops were really coming into use. This find has the power to really re-shape what we think of the history of brewing and hopped beverages. Neat stuff.

There is a publication which details the find (and its numerous artifacts) which you can obtain here; of course, the entire thing is available exclusively in German, so you may have to find a linguistically-inclined friend to help you out with it. Fortunately, I have some connections, and I managed to acquire the part of the journal detailing the bottle find. A bit of OCR, Google translate, dictionary consultation, and linguistically-inclined friend consultation, and I managed to figure out most of what the find was about.

Evidently, there was pollen residue in the bottle (~3500 grains), and researchers were able to identify the sources of the pollen grains:

If my translation is right, the contribution is 17% barley, 11% cereal weeds (possibly rye or oats?), 0.4% hops, 0.4% grapes, and 29% “bee pollen” (which is taken as a marker of honey). The bottle also contained evidence of fermentation (oxalate crystals), and so the author concludes that the beverage was probably a mixture of the above ingredients in the mentioned proportions, fermented together and hopped. The beer came first, and it was “enriched” with honey – or so the author concludes.

But I don’t like that analysis. For one thing, the author doesn’t seem to try to figure out the actual proportions of the plant matter represented by the pollen; the text seems to assume that all ingredients will convey the same amount of pollen, which may not be the case. They also don’t elaborate too much on their rationale for their experiments or on the type of hop present – which is too bad, because this is a pretty big find!

So let’s tear this down and show how you can extrapolate a recipe from scant information. What if you wanted to try recreating a beverage like this? No recipe, no method, just some pollen grains in a bottle – how can we do it?

Watch and learn.

That feel whenever you take off autopilot and try to land the science jet yourself.

When we do this kind of analysis, we often have to make lots and lots of assumptions and extrapolations. In archaeology, the variables are often well beyond our control – so experimental archaeology must try to control what it can or accept the limitations of uncontrolled variables. I’ve advocated a sort of “mapping” approach to redacting and analyzing ancient recipes, and that principle will aid us here as well; by listing out my assumptions and reasoning, I can go back and nitpick and refine and strengthen my arguments.

The goal here is to get to something that resembles a more accurate technique, and in the process to enumerate some other possible and plausible methods. Most of the time, these sorts of analyses are rarely definitive, and tend to leave us with more questions than when we started – but it helps us to focus our inquiries, so that our questioning can be more productive. This is the heart of science.

Let us assume:

1) That a total of 28% of the 3500 pollen grains are attributable directly to barley which has been malted (that would be 17% attributed mostly to barley and 11% attributed to “cereal” weeds – we know that barley is not generally insect-pollinated, so the “bee pollen” probably does not cross with this group);

2) That 29% of the pollen grains are attributable to raw honey (bee pollen shows up often in raw honey);

3) That 0.4% of the pollen grains are attributable to Hallertau hops (they’re alleged to be the first hops that were ever domesticated, and the Trossingen area was close-ish to Hallertau);

4) That 0.4% of the pollen grains are attributable to grapes (though as you will see shortly, I haven’t rolled grapes into my analysis yet because I can’t find information about them);

5) That the ingredients were fermented together in a single beverage (as opposed to the pollen contribution coming from, say, 3 different beverages which all touched the bottle at some point);

7) That a single kernel of dry barley weighs one grain (0.06 grams – the origin of the term “grain” is the weight of one kernel of barley), and that malted barley is ~10% less dense than unmalted barley;

9) That hops used were wild, and thus grew at a ratio of 1:1 male:female plants (hops are a dioecious plant, and wild-type examples of such plants grow in a ratio pretty close to 1:1 – this indicates that the pollen load of a male plant reported represents a single female flower);

10) That hops pollinate in a manner similar to their nearest botanical relative, Cannabis (note that hops are a cannaboid) – which produces an average of 36,500 pollen grains per male flower;

11) That the mechanism of wind pollination results in ~95% of the pollen accumulating on the windward (i.e. exterior) surfaces of the plant, and that this pollen load would be removed in hop processing (i.e. the pollen that didn’t make it into the interior of the female flower just falls off);

12) That there are 100 wet hop flowers (we use the female flower of the hop in brewing) per 50 grams of hops, or 0.5 grams wet per hop flower (which translates to roughly 0.1 grams per dried flower);

13) And that these estimates actually apply to 6th century German plants.

Y’know, I never noticed the completely incredulous look on his face until right now.

So, basically, I’m making shit up. “Educated guesses” if you’re feeling generous – but I’m basically winging it in the absence of any more useful information.

One thing that we can definitely see by my analysis so far: it is a great mistake to assume that all of the ingredients going into a beverage would have the same pollen representation per gram.

Let’s look at my numbers. Each barley grain produces 2250 pollen grains, each gram of honey has 6000 pollen grains, and each hop flower has 1825 pollen grains (5% of 36.5k). Let’s convert these to a standard measure: pollen grains per gram of plant matter.

Barley: 37.5k pg/g
Honey: 6k pg/g
Hops: 3650 pg/g

Now, how about the proportional representation of pollen grains in the find? 3500 pollen grains total, so:

Barley: 28% = 980 pg
Honey: 29% = 1015 pg
Hops: 0.4% = 14 pg

And then we just do the math to figure out the possible mass of plant matter that delivered that pollen load!

Barley: 0.026 g
Honey: 0.17 g
Hops: 0.0038 g wet (1/5 as much dried)

That gives us a ratio of barley:honey:wet hops (by weight) of 26:170:3.8, or to make things easier: 7:45:1

So let’s turn this into amounts that make more sense, shall we? Let’s also not forget that malted barley weighs 10% less than “green” barley:

The first thing I notice straight away – this ain’t a barley beer. Not by any stretch. The mass of barley is so small that it really seems much more like a flavoring or additive than anything else. The vast majority of sugar here is coming from the honey – enough that I’d really call this a “mead.”

Of course, as you will remember, the word “beor” (which is a root of “beer”) is glossed with “hydromel,” which refers to a honey-based strong beverage. So really, it’s not outside the realm of possibility that one could call a honey-based drink a “beer” in the ancient world – it seems to have fulfilled that role.

Pliny specifically discusses the various methods of making “leaven,” and one method is to incorporate grape must into barley flour and make a biscuit. Grape must incorporated into such a “bread” as I’ve talked about previously could explain the grape pollen in the original find. The use of herbs in the bread may give us a clue as to how the hops came into play; perhaps grape must and hops were mixed into barley flour, and the resultant “cake” was used as a yeast starter to then ferment a honey/water solution.

We can make a wide number of recipes simply by varying the amount of water that goes into such a thing. Generally, “hydromel” was a 1:4 honey:water ratio. A pound of honey occupies a space of about 10 fluid ounces, so we’d need about 40 fluid ounces of water to properly dilute that honey. Do that, add in your 65 grams of barley/dried hop mix (which has been previously fermented), and wait a bit. Yeast from the grapes eat those sugars, and you get a little more than a quart (about 1.5) of slightly hopped mead.

How hopped? Well, 2 dried grams of hops at that density of sugar yields ~12 IBU – roughly the same bittering content of Budweiser. For reference, an English Ordinary bitter is somewhere in the 25 – 35 IBU range. American pale ales are in the 50’s, and IPAs are up in the 70’s or more.

You could even add a bit more water – maybe go to half a gallon of final volume (1:5 ratio) with all that honey, which would give you a lighter-bodied beer with only 8 IBU. A little less sweet, a little less hoppy. The evidence still supports such an idea. Hell, it supports a lot of ideas.

Or you could go heavier (1:3 ratio) and make something really sweet with about 16 IBU. It’s all up to you and what you prefer!

Therefore, based on my analysis of the evidence, I conclude that the Trossingen bottle may have contained the remnants of a lightly hopped mead, which may have been fermented using the residue of a light grain fermentation.

The lesson here: archaeological evidence always requires interpretation. Using the same set of facts, we can come up with very different conclusions simply by varying the manner of our interpretation and the set of assumptions used to perform an analysis.

This is far from a definitive answer. I have thirteen listed assumptions, any variation on any of which can completely alter my outcome. I have no idea how much water was added, or how long it was fermented, or what proportion the grapes represent. We could re-analyze the model with an attempt to figure out what “cereal weeds” means and re-evaluate the contribution of plant matter from those (here’s a hint: rye produces ~10x the pollen that barley does – so there may be even less grain in this recipe than I’ve indicated).

But at least for now, I have something to work with – and that’s how science works.

The use of hops with mead is already documented in a Frankish fifth century grave from Cologne. Several sources report Fremersdorf’s results (second-hand), including this article on a separate subject:

I believe Pat McGovern’s most recent paper (the “Nordic Grog” one I talked about previously) indicated the presence of wormwood in a beverage, and we have documentary evidence that wormwood was used by the Romans. Again, given cultural contact and demonstrable artifact exchange, it seems plausible that the tradition may have promulgated north. That makes some sense.

I do question the degree of bittering that would have been imparted by the hops as-used. Of course, we’re also not exactly sure where they were added in the process, and processing will affect their contribution to the beverage rather extraordinarily. I tend to think they were probably used as a pre-alcohol fermentation additive (as I’ve talked about), or possibly added as an aromatic to the finished beverage.

The presence of pollen at all would lead me to believe that they were using wild hops (or at least hops cultivated more “naturally” than we do today), and that the hops were probably allowed to flower and go to seed before use. Later hop finds seem to involve fruits and seeds as well, so it seems that there is evidence of pollinated hop use. I know that pollinated hops behave differently in a beverage than non-pollinated ones – so that’s a thing to try out one of these days.

But, I mean, they could’ve made a hop tea and added it. That’s plausible too.

[…] of a recipe are not quite as important to me as the mindset. I’ve done specific recipes and painstaking analyses of pollen residues in pursuit of reconstructing booze, and while I’m going to continue my crazy-ass experiments […]

Tremendous work. What I would love to know is how much protection against infection of the drink a small amount of unboiled hops would have given – has anyone done any experiments? I know the antibacterial elements in meadowsweet are supposed to give two or three months of protection to a drink when added …

Wow, I take that as very high praise coming from you! I’ve been reading Zythophile for years now! Thanks for dropping in!

“What I would love to know is how much protection against infection of the drink a small amount of unboiled hops would have given..”

That’s a good question. I’ve been trying to find information about acid extraction at cooler temperatures, but there doesn’t seem to be a lot of research in that department. I hear “you need boiling temperatures to isomerize the acids” all the time, but no solid research about why that is the case or about the kinetics of the system.

It’s at those times I remember that brewing is still at its heart a vocation and not a field of science – if it works, why fix it?

But in my various digging at Early Middle Ages brewing, I’ve come to the conclusion that short shelf life was a bigger factor than herbal preservation. A lot of these beverages were being prepared daily in small quantities, or on demand for occasions when they were intended to be completely consumed. Aged beverages – like wine and mead – were held in high esteem, and I believe it’s at least in part because the ability to preserve a beverage for a time was rare and noteworthy.

A friend of mine lobbed an article (from a 2004 German archaeology publication) my way a few days ago, and it adds a new twist to the situation. They managed to strain-type the cereals in the grave – and found that the dominant strain of barley was of a variety native to Iraq. Prior to this dig, the strain had not been seen in continental Europe until ~1000 years later.

It seems plausible that the grain used for this beverage was being imported – or perhaps the beverage was imported, or perhaps this person was a traveler who made it to Persia and either had a new beverage or brought a tradition home with him.

A later Persian work in fact gives a recipe for a drink made from a weak grain base with a lot of honey added to it – and it includes floral herb additions. It was intended as a non-alcoholic “soda,” for lack of a better analogue.

So maybe this isn’t even a mead at all. Maybe the hops were never intended for bittering. Maybe they used them as the full flower and not the immature “cone” we use in brewing today.

Honestly, I don’t know that any fermented drinks were all that long lasting. Wine may have lasted longer than beer, but not by much. The Romans had had vintage wines, using amphorae, but it’s been suggested that one reason these disappeared was that the Gauls used barrels, which took some time to become air tight. I don’t know that mead was ever aged.

I don’t think hops were used for their preservative qualities for quite some time. I don’t even know that early drinkers were aware of these. Certainly it’s striking that they were used in the eighth century in a monastery, but did not come into general use until centuries later.

Regarding the strain of barley, could it not simply be that the variety grown in Europe was descended from Persian seeds? It would probably take some reading through carpological reports from the period to narrow this down.

RE: Barley: It would be possible, yes, but we have no other evidence from other grain finds in historical continental Europe until much later. This is essentially an anomalous find among countless other grain finds, which makes it compelling.

Obviously, absence of evidence is not evidence of absence – but if they were being grown notably in Europe at the time, we could reasonably expect to find other evidence of this barley elsewhere. That we don’t could very well be significant. And given that barley is native to continental Europe anyhow, does it make sense to import a Persian barley for general use? I tend to think it likely that there was a particular impetus behind the acquisition of this strain.

So I’m really exploring the possibility that the grain is of particular significance. Not necessarily saying that it is, but what if?

RE: Hops: I don’t know if they were particularly aware of hops as a preservative or not; I tend to think that they probably didn’t think it had any particular preservative quality, and probably used them like they would have used any other herbal addition (i.e. when they had it, liked it, thought it was appropriate, or had a particular use in mind). One question I’ve been poking at is the state of hops in use at this time. We don’t have much evidence of hop cultivation until later, and the Corby decree is noteworthy for talking about gathering hops from the wild – implying a non-cultivated plant. The later Graveney boat find is loaded with hop seeds – implying pollinated hops.

Today, we only grow the female plants for use in brewing. But what are the properties of non-cultivated hops that are pollinated routinely? Do the flavors change? The acid profile? If they used fruiting hops, would the seeds and/or fruits have gone in as well?

Hops is a hot and dry herb, with a bit of moisture. It is not much use for a human being, since it causes his melancholy to increase, gives him a sad mind, and makes his intestines heavy. Nevertheless its bitterness inhibits some spoilage in beverages to which it is added, making them last longer. (p.36)

Oh yes, absolutely by Hildegarde! My question is more concerned with when this knowledge came to be. We know it was there by Hildegarde, and we don’t find this knowledge earlier (that I know of) – so did 6th century Merovingians know of the preservative properties of hops?

I can’t tell one way or another. One thing I want to do is try this beverage with multiple different hop usage cases and see what kind of difference it makes.